513 research outputs found
Carbon Nanotubes Enhanced The Lead Toxicity On The Freshwater Fish
Carbon nanotubes are promising nanostructures for many applications in materials industry and biotechnology. However, it is mandatory to evaluate their toxicity and environmental implications. We evaluated nitric acid treated multiwalled carbon nanotubes (HNO3-MWCNT) toxicity in Nile tilapia (Oreochromis niloticus) and also the lead (Pb) toxicity modulation after the nanotube interaction. Industrial grade multiwalled carbon nanotubes [Ctube 100, CNT Co. Ltd] were treated with 9M HNO3 for 12h at 150°C to generate oxygenated groups on the nanotube surface, to improve water dispersion and heavy metal interaction. The HNO3-treated multiwalled carbon nanotubes were physico-chemically characterized by several techniques [e.g. TEM, FE-SEM, TGA, ζ-potential and Raman spectroscopy]. HNO3-MWCNT did not show toxicity on Nile tilapia when the concentration ranged from 0.1 to 3.0 mg/L, and the maximum exposure time was 96h. After 24, 48, 72 and 96h the LC50 values of Pb were 1.65, 1.32, 1.10 and 0.99 mg/L, respectively. To evaluate the Pb-nanotube interaction influence on the ecotoxicity, we submitted the Nile tilapia to different concentrations of Pb mixed with a non-toxic concentration of HNO3-MWCNT (1.0 mg/L). After 24, 48, 72, 96 h the LC50 values of Pb plus nanotubes were: 0.32, 0.25, 0.20, 0.18 mg/L, respectively. These values showed a synergistic effect after Pb-nanotube interaction since Pb toxicity increased over five times. X-ray energy dispersive spectroscopy (EDS) was used to confirm lead adsorption on the carbon nanotube oxidized surface. The exposure of Nile tilapia to Pb plus HNO3-MWCNT caused both oxygen consumption and ammonium excretion decrease, when compared to the control. Finally, our results show that carbon nanotubes interact with classical pollutants drawing attention to the environmental implications. © IOP Publishing Ltd 2013.4291Stéfani, D., Paula, A.J., Vaz, B.G., Silva, R.A., Andrade, N.F., Justo, G.Z., Ferreira, C.V., Alves, O.L., Structural and proactive safety aspects of oxidation debris from multiwalled carbon nanotubes (2011) J. Hazardous Materials, 189 (1-2), pp. 391-396. , 10.1016/j.jhazmat.2011.02.050 0304-3894Datsyuk, V., Kalyva, M., Papagelis, K., Parthenios, J., Tasis, D., Siokou, A., Kallitsis, I., Galiotis, C., Chemical oxidation of multiwalled carbon nanotubes (2008) Carbon, 46 (6), pp. 833-840. , 10.1016/j.carbon.2008.02.012 0008-6223Marques, R.R.N., MacHado, B.F., Faria, J.L., Silva, A.M.T., Controlled generation of oxygen functionalities on the surface of Single-Walled Carbon Nanotubes by HNO3 hydrothermal oxidation Carbon, 48 (5), pp. 1515-1523Wu, W.H., Chen, W., Lin, D.H., Yang, K., Influence of Surface Oxidation of Multiwalled Carbon Nanotubes on the Adsorption Affinity and Capacity of Polar and Nonpolar Organic Compounds in Aqueous Phase (2012) Environmental Sci. Technol., 46 (10), pp. 5446-5454. , 10.1021/es3004848 0013-936XDai, W., Liu, S.X., Fu, L.L., Du, H.H., Xu, Z.R., Lead (Pb) accumulation, oxidative stress and DNA damage induced by dietary Pb in tilapia (Oreochromis niloticus) (2012) Aquaculture Research, 43 (2), pp. 208-214. , 10.1111/j.1365-2109.2011.02817.x 1355-557XUmbuzeiro, G.A., Coluci, V.R., Honorio, J.G., Giro, R., Moraes, D.A., Lage, A.S.G., Mazzei, J.L., Alves, O.L., Understanding the interaction of multi-walled carbon nanotubes with mutagenic organic pollutants using computational modeling and biological experiments (2011) TRAC Trends Analytical Chem., 30 (3), pp. 437-446. , 10.1016/j.trac.2010.11.013 0165-9936Navarro, R.D., Navarro, F.K.S.P., Ribeiro, O.P., Ferreira, W.M., Pereira, M.M., Seixas, J.T., Quality of polyunsaturated fatty acids in Nile tilapias (Oreochromis niloticus) fed with vitamin e supplementation (2012) Food Chem., 134 (1), pp. 215-218. , 10.1016/j.foodchem.2012.02.097 0308-8146Kaya, H., Akbulut, M., Celik, E.S., Yilmaz, S., Aydin, F., Duysak, M., Effects of lead nitrate on haematological and immunological parameters in the tilapia (Oreochromis mossambicus, L. 1758) (2011) Toxicology Lett., 205, pp. 128-S132. , 10.1016/j.toxlet.2011.05.457 0378-4274Rashed, M.N., Cadmium and lead levels in fish (Tilapia nilotica) tissues as biological indicator for lake water pollution (2011) Environmental Monitoring Assessment, 68 (1), pp. 75-89. , 10.1023/A:1010739023662 0167-6369Wang, X., Acute toxicity and synergism of binary mixtures of antifouling biocides with heavy metals to embryos of sea urchin Glyptocidaris crenularis (2011) Human Experimental Toxicology, 30 (8), pp. 1009-1021. , 10.1177/0960327110385958 0960-3271Li, Y.H., Wang, S.G., Wei, J.Q., Zhang, X.F., Xu, C.L., Luan, Z.K., Wu, D.H., Wei, B.Q., Lead adsorption on carbon nanotubes (2002) Chem. Phys. Lett., 357 (3-4), pp. 263-266. , 10.1016/S0009-2614(02)00502-X 0009-2614Yu, X.Y., Luo, T., Zhang, Y.X., Jia, Y., Zhu, B.J., Fu, X.C., Liu, J.H., Huang, X.J., Adsorption of Lead(II) on O-2-Plasma-Oxidized Multiwalled Carbon Nanotubes: Thermodynamics, Kinetics, and Desorption (2011) ACS Appl. Materials Interfaces, 3 (7), pp. 2585-2593. , 10.1021/am2004202 1944-8244Barbieri, E., Paes, E.T., The use of oxygen consumption and ammonium excretion to evaluate the toxicity of cadmium on Farfantepenaeus paulensis with respect to salinity (2011) Chemosphere, 84 (1), pp. 9-16. , 10.1016/j.chemosphere.2011.02.092 0045-653
Changes in growth of tropical forests: evaluating potential biases
Over the past century almost every ecosystem on Earth has come under the
influence of changes in atmospheric composition and climate caused by human activity.
Tropical forests are among the most productive and extensive ecosystems, and it has been
hypothesized that both the dynamics and biomass of apparently undisturbed, old-growth
tropical forests have been changing in response to atmospheric changes. Long-term forest
sample plots are a critical tool in detecting and monitoring such changes, and our recent
analysis of pan-tropical-forest plot data has suggested that the biomass of tropical forests
has been increasing, providing a modest negative feedback on the rate of accumulation of
atmospheric CO2. However, it has been argued that some of these old forest plot data sets
have significant problems in interpretation because of the use of nonstandardized methodologies.
In this paper we examine the extent to which potential field methodological errors may
bias estimates of total biomass change by detailed examination of tree-by-tree records from
up to 120 Neotropical plots to test predictions from theory. Potential positive biases on
measurements of biomass change include a bias in site selection, tree deformities introduced
by the measurement process, poor methodologies to deal with tree deformities or buttresses,
and nonrecording of negative growth increments. We show that, while it is important to
improve and standardize methodologies in current and future forest-plot work, any systematic
errors introduced by currently identified biases in past studies are small and calculable.
We conclude that most tropical-forest plot data are of useful quality, and that the evidence
does still weigh conclusively in favor of a recent increase of biomass in old-growth tropical
forests
An international network to monitor the structure, composition and dynamics of Amazonian forests (RAINFOR)
The Amazon basin is likely to be increasingly affected by environmental changes: higher temperatures, changes in precipitation, CO2 fertilization and habitat fragmentation. To examine the important ecological and biogeochemical consequences of these changes, we are developing an international network, RAINFOR, which aims to monitor forest biomass and dynamics across Amazonia in a co-ordinated fashion in order to understand their relationship to soil and climate. The network will focus on sample plots established by independent researchers, some providing data extending back several decades. We will also conduct rapid transect studies of poorly monitored regions. Field expeditions analysed local soil and plant properties in the first phase (2001–2002). Initial results suggest that the network has the potential to reveal much information on the continental-scale relations between forest and environment. The network will also serve as a forum for discussion between researchers, with the aim of standardising sampling techniques and methodologies that will enable Amazonian forests to be monitored in a coherent manner in the coming decades
Design and evaluation of a treatment programme for Spanish adolescents with overweight and obesity. The EVASYON Study
Background
The prevalence of overweight and obesity (OW/OB) among adolescents worldwide has increased since the 60 s. Spain has reached one of the highest OW/OB prevalence rates among adolescents from European countries. The aim of this methodological paper is to describe the design and evaluation in the EVASYON study (Development, implementation and evaluation of the efficacy of a therapeutic programme for adolescents with OW/OB: integral education on nutrition and physical activity).
Methods/Design
The EVASYON was planned by a multidisciplinary team to treat OW/OB in Spanish adolescents. The EVASYON is a multi-centre study conducted in 5 hospitals in 5 Spanish cities (Granada, Madrid, Pamplona, Santander and Zaragoza) and two hundred and four OW/OB Spanish adolescents were recruited for this intervention. The treatment was implemented for approximately one-year follow-up. The adolescents were treated in groups of a maximum of 10 subjects; each group had 20 visits during the treatment period in two phases: intensive during the first 2 months (1st to 9th visits), and extensive during the last 11 months (10th to 20th visits). In order to assess the efficacy of the treatment, 8 dimensions were measured: diet; physical activity and fitness; eating behaviour; body composition; haematological profile; metabolic profile; minerals and vitamins; immuno-inflammatory markers. Moreover, genetic polymorphisms were also determined.
Discussion
The treatment programme developed in the EVASYON study was designed as a national pilot study to be implemented as an effective treatment for adolescents with OW/OB into the Spanish Health Care Service
Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector
A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results
Jet size dependence of single jet suppression in lead-lead collisions at sqrt(s(NN)) = 2.76 TeV with the ATLAS detector at the LHC
Measurements of inclusive jet suppression in heavy ion collisions at the LHC
provide direct sensitivity to the physics of jet quenching. In a sample of
lead-lead collisions at sqrt(s) = 2.76 TeV corresponding to an integrated
luminosity of approximately 7 inverse microbarns, ATLAS has measured jets with
a calorimeter over the pseudorapidity interval |eta| < 2.1 and over the
transverse momentum range 38 < pT < 210 GeV. Jets were reconstructed using the
anti-kt algorithm with values for the distance parameter that determines the
nominal jet radius of R = 0.2, 0.3, 0.4 and 0.5. The centrality dependence of
the jet yield is characterized by the jet "central-to-peripheral ratio," Rcp.
Jet production is found to be suppressed by approximately a factor of two in
the 10% most central collisions relative to peripheral collisions. Rcp varies
smoothly with centrality as characterized by the number of participating
nucleons. The observed suppression is only weakly dependent on jet radius and
transverse momentum. These results provide the first direct measurement of
inclusive jet suppression in heavy ion collisions and complement previous
measurements of dijet transverse energy imbalance at the LHC.Comment: 15 pages plus author list (30 pages total), 8 figures, 2 tables,
submitted to Physics Letters B. All figures including auxiliary figures are
available at
http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HION-2011-02
Search for displaced vertices arising from decays of new heavy particles in 7 TeV pp collisions at ATLAS
We present the results of a search for new, heavy particles that decay at a
significant distance from their production point into a final state containing
charged hadrons in association with a high-momentum muon. The search is
conducted in a pp-collision data sample with a center-of-mass energy of 7 TeV
and an integrated luminosity of 33 pb^-1 collected in 2010 by the ATLAS
detector operating at the Large Hadron Collider. Production of such particles
is expected in various scenarios of physics beyond the standard model. We
observe no signal and place limits on the production cross-section of
supersymmetric particles in an R-parity-violating scenario as a function of the
neutralino lifetime. Limits are presented for different squark and neutralino
masses, enabling extension of the limits to a variety of other models.Comment: 8 pages plus author list (20 pages total), 8 figures, 1 table, final
version to appear in Physics Letters
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